<p>Chimpanzee sorting task dataset.</p>

Discrimination learning tasks are a method for investigating species’ perception of and associative learning with a particular stimulus. Goffin’s cockatoos previously required surprisingly few trials to differentiate objects based on weight alone in a simple discrimination task, outperforming primates in other weight discrimination setups. Nevertheless, it was unclear whether the difference in performance was largely based on ability or differences in experimental procedures. Therefore, we tested a group of Goffin’s cockatoos on a weight-based conditional discrimination, like a task previously used with chimpanzees. Similar to the chimpanzees (compared to their first 15 sessions), none of our subjects reached above-chance levels of performance in the present study. The contrasting performance of our cockatoos in the two weight discrimination studies are in line with the idea that conditional discriminations are more cognitively demanding than simple discriminations. Our results do not support the notion of a distinct difference between birds and primates in their arbitrary discrimination learning abilities with weight cues. However, further research on this question (we suggest with simple discrimination formats) would be necessary.辨别学习任务（discrimination learning tasks）是用于探究物种对特定刺激的感知与联想学习能力的研究方法。此前研究表明，戈芬凤头鹦鹉（Goffin’s cockatoos）仅需极少试次即可在简单辨别任务中仅依靠重量区分物体，在其他重量辨别实验范式中的表现优于灵长类动物。然而，目前尚不清楚二者的表现差异主要源于物种自身能力的不同，还是实验程序的差异。因此，本研究采用此前用于黑猩猩的基于重量的条件辨别任务（weight-based conditional discrimination），对一组戈芬凤头鹦鹉开展测试。与此前研究中的黑猩猩（对比其前15个实验阶段）类似，本研究中所有受试个体均未达到高于随机猜测的表现水平。戈芬凤头鹦鹉在两项重量辨别研究中的表现差异，印证了“条件辨别任务比简单辨别任务具有更高认知负荷”这一观点。本研究结果不支持“鸟类与灵长类在依靠重量线索进行任意辨别学习的能力上存在显著差异”这一论点。不过，针对该问题仍需开展进一步研究（本研究建议采用简单辨别任务范式）。